The present technology relates to a semiconductor device, an antenna switch circuit, and a radio communication apparatus. More specifically, the present technology relates to a semiconductor device having a channel layer that is configured of a compound semiconductor, an antenna switch circuit that includes such a semiconductor device, and a radio communication apparatus that includes such an antenna switch circuit.
In recent years, in a mobile communication system such as a mobile phone, reduction in size and power consumption of a mobile communication terminal has been important considerations. To fulfill such considerations, for example, concerning an antenna switch, reduction in on-resistance Ron and off-capacitance Coff, and the like may be preferred. One of devices that have been currently put to practical use for such an antenna switch is a JPHEMT (Junction Pseudo-morphic High Electron Mobility Transistor).
The JPHEMT is a semiconductor device that performs current modulation utilizing a p-n junction and a heterojunction. Such a semiconductor device includes a heterojunction with a channel layer made of, for example, InGaAs and a barrier layer (AlGaAs) made of, for example, AlGaAs that is wider than the channel layer (InGaAs) in a bandgap. Inside the barrier layer (AlGaAs), a first low-resistance region containing reverse-conductivity impurities is provided on a surface layer on the opposite side of the channel layer, and a gate electrode is connected with this first low-resistance region. Further, inside the barrier layer (AlGaAs), a carrier supply region containing impurities that serve as carriers is provided on the channel layer side that is away from the first low-resistance region. Furthermore, a source electrode and a drain electrode are ohmic-bonded to the barrier layer (AlGaAs) on both sides of the first low-resistance region and the gate electrode.
In the semiconductor device that is configured as described above, a two-dimensional electron gas layer in which electrons serving as carriers are confined in a high concentration is formed at an interface on the side of the barrier layer in the channel layer. By applying a voltage to the gate electrode to control the concentration of the two-dimensional electron gas layer, a current is modulated that flows between the source electrode and the drain electrode via a channel layer portion on the lower side of the first low-resistance region (for example, see Japanese Unexamined Patent Application Publication No. H11-150264).